The Return of the Cobbers

Yesterday we finished off the plastering of Jerry's cob oven. The only thing left is to coat it with boiled linseed oil to help protect it from inclement weather.

On Memorial Day Jerry and I began screening all the components. We put the sand through window screen to get out the little pieces of gravel which will mar the surface of the plaster when you're troweling it smooth. We screened the soil and straw too, and I picked lumps of horse manure out of the mess I'd scooped up in Annadel State Park. We ended us screening those with the wider mesh screen the next day when Krista joined us.

We mixed it all up in a plastic tub, using a shovel and a drill with a paddle bit. In hindsight I would've skipped the straw entirely and used more horse manure. It has the perfect kind of fiber for plaster, and to my surprise it didn't smell at all. The straw, even though we'd screened it three times, ended up showing up on the surface of the plaster, just a bit. Cattail fluff would have been better, but it was out of season.

Because the surface of the cob oven was already sculpted into snail shell ridges, we applied the plaster by hand. I think we could've gone back over the sides with a trowel though. They ended up just a bit lumpier than I'd have liked. Even if we had used trowels though, I think putting on with our hands was essential to really work it in. We had made a gazillion little thumb sized divots so that this coat would adhere, and there was a lot of straw sticking out that had to be worked around.

After the plaster had set for an hour or so, we took smooth plastic lids from yogurt tubs and smoothed it down. This was challenging around all the ridges, but incredibly satisfying to me. The oven ended up looking smooth and almost shiny.
It would have been interesting to have added pigment to the plaster. Perhaps a dark orange color? It ended up looking pale tan, but that will change with the linseed oil, which has a tendency to darken the clay.

All in all a wonderful project. I think the pizzas will taste even better now, if that's possible!

To see photos of the entire project, you can visit my Flickr set by clicking here. Most of the photos have notes.

Good Fences

I've been thinking about fencing today. Meredith and Steve have about 95 feet of crappy old wood fence that needs replacing. Steve told me that having it done will cost over $4,000 and he's thinking redwood. Ugh.
So I got to thinking about the 'light straw clay' construction that I got to experience last summer. It's a wonderful system for dwelling walls. What about fencing?
This photo shows light straw clay walls going up for a laundry room with 8' ceilings and a window. The wall to the right is finished and waiting for plaster.
I'm thinking one could sink metal poles using concrete (not green, I know, but termite proof). I think the poles for chain link fence probably have holes pre-drilled. Otherwise a shop could do it for you.
I'd want to use 2x6's for extra wall thickness. So I'd attach a 2x6 to the post with a few bolts, so the wood would be off the ground and perpendicular to the line of the fence.
2x6 top and bottom boards go horizontal with a vertical piece joining them half way at four feet. I would probably add vertical bamboo inside the structure for extra support. Bamboo or any straight saplings or even old pipe or whatnot.
Once the structure is up, removable plywood forms are used to apply the light strawclay. This goes up pretty quick, using a little less than one bale per 8 feet.
Basically, the straw is mixed with clay slip on a tarp, using a hoe or hands, then tamped into the cavity between the plywood forms. It sets up quick and becomes very sturdy and sound proof.
I think a crew of three or four people could do the 95 feet in a day, easy.
But then would come mud plastering. That would need a work crew or maybe some day laborers? And probably two coats. Using natural plaster, almost all the cost would be in the labor (which might even be free).
This photo shows the same wall as above with a few coats of earthen plaster, essentially finished.

The two parts I'm not sure of are the cap and the bottom of the fence. A cap of some kind would help keep water off the plaster, especially if it had a drip edge. I know PVC pipe is pure evil, but I can imagine cutting a big one in two and laying it over the 2x6 top of the fence, with the edges overhanging. We could wrap it in some chicken wire and plaster over it with stucco. Just an idea.
The bottom of the fence could leave an open gap, but I like the idea of it being supported by the ground. I just don't know about termites migrating through the ground up into the wood. More research needed.
Anyhow, I've tried to find out if anyone else has built a fence this way. If so, they haven't put it up on the web.
I think it's a pretty good idea. Since the wood would all be encased in plaster, it should last for a long long time. It would need to be re plastered occasionally, but with a good roof cap I think it would need far less maintenance than any wooden fence. And it would be cheap. Even using new lumber I priced it out at $475 for materials for the 95 feet. And you'd have a very private, sound blocking and good looking fence.
If you have any thoughts on this project idea, especially if you see a glaring problem I've overlooked, please leave a comment!